Air Flow Measuring Device with Convex Tube Body
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Solution Overview
Problem
Existing air flow measuring devices face challenges in accurately detecting air flow due to dispersion, disturbance, or variation caused by an air cleaner upstream, leading to unstable air flow speed and reduced detection accuracy.
Innovation Solution
The air flow measuring device incorporates a tube body with a bypass passage and a sub-bypass passage, featuring a convex curve surface and varying outer diameters to minimize air disturbance and maintain stable pressure differences, thereby improving the accuracy of the flow amount sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional sensor body with bypass passage is used, then the flow amount can be measured, but the detection accuracy is deteriorated due to air flow separation and large swirl caused by upstream air disturbance
Solution Approach 1:
The tube body is designed with a convex curve surface instead of a straight cylindrical shape. The convex curve surface has a radius of curvature R that satisfies 0 < R ≤ L/2 (where L is the length of the tube body), creating a streamlined shape that reduces air flow separation and disturbance, thereby improving detection accuracy of the flow amount sensor
Solution Approach 2:
The patent changes the geometric parameters of the tube body by introducing a convex curve surface with specific radius of curvature R. This parameter modification optimizes the air flow characteristics around the tube body, reducing harmful flow separation and swirl effects that would otherwise degrade measurement precision
2Device complexity
If the tube body has a straight cylindrical shape, then the structure is simple, but the pressure resistance of air is large causing unstable flow speed and reduced detection accuracy
Solution Approach 1:
The tube body is designed with a convex curve surface instead of a straight cylindrical shape. The convex curve surface has a radius of curvature R that satisfies 0 < R ≤ L/2 (where L is the length of the tube body), creating a streamlined shape that reduces air flow separation and disturbance, thereby improving detection accuracy of the flow amount sensor
Solution Approach 2:
The convex curve surface is designed upstream of the tube body to preliminarily guide and smooth the air flow before it reaches the bypass passage inlet. This preliminary flow conditioning prevents turbulence and separation, ensuring stable flow speed enters the measurement section
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design stabilizes air flow speed in the bypass passage, reducing variations and enhancing the detection accuracy of the flow amount sensor by minimizing air separation and pressure differences.
Implementation Method 1
the pressure resistance of air on the tube body can be made small, thereby restricting a large disturbance of air flowing along the outer peripheral surface of the tube body
Implementation Method 2
a flow speed of air flowing in the bypass passage can be made stable without greatly changing a pressure difference between the inlet and outlet of the bypass passage
Data Source
AI summary
An air flow measuring device includes a flow amount sensor for measuring a flow amount of air in a duct, and a tube body for defining a bypass passage in the duct. An upstream end surface of the tube body has an inlet of the bypass passage, and a downstream end surface thereof has an outlet of the bypass passage. An outer diameter of an outer peripheral surface of the tube body has a smallest dimension at the upstream end surface, and a largest dimension at the downstream end surface. Furthermore, the outer peripheral surface of the tube body has an upstream portion extending downstream from the upstream end surface in a predetermined range, and the upstream portion of the outer peripheral surface is a convex curve surface in which the outer diameter is increased by a ratio from the upstream end surface toward downstream.